1. Field of the Invention
The present invention relates to a chemical processor and a chemical processing method for subjecting a member to be processed, such as a semiconductor wafer, to chemical processing, as well as to a method of manufacturing a semiconductor device using the processor and method.
2. Background Art
A semiconductor device is generally produced from a semiconductor wafer made of group IV compounds such as silicon or III–V group compounds such as gallium arsenide. Via holes penetrating through a semiconductor substrate from the front to back thereof are formed in a finished semiconductor device for establishing electrical contact with ground electrodes provided on the back of a semiconductor substrate formed by slicing a semiconductor wafer. In many cases, the via holes are subjected to chemical processing, such as that pertaining to a cleaning process and that pertaining to a plating process. A semiconductor wafer which has not yet been separated into a plurality of semiconductor devices is subjected to processing pertaining to the cleaning process and that pertaining to the plating process. Via holes are formed in areas of the semiconductor wafer which are to become semiconductor substrates of a plurality of semiconductor devices. The semiconductor wafer is subjected to processing pertaining to the cleaning process and that pertaining to the plating process while an opening provided at one end of each via hole is closed; that is, while the via holes are held in the form of blind holes.
During the cleaning process, contaminants, and etch residues or resist residues which remain in blind holes are removed. For instance, during a process for manufacturing a semiconductor device having such blind holes, blind holes are formed through, e.g., reactive ion etching. Organic polymer residues and resist residues, which include carbon and chloride produced during reactive ion etching, still remain in the blind holes formed through reactive ion etching. Hence, before proceeding to the plating process, the wafer is subjected to processing pertaining to the cleaning process for removing the residues.
In many cases, interior surfaces of the blind holes are plated with gold (Au). Processing pertaining to the plating process is performed subsequent to that pertaining to the cleaning process. A plating layer is formed on the interior surfaces of the respective via holes formed in the form of blind holes. Processing pertaining to the plating process includes electroless plating and electrolytic plating.
Processing pertaining to the cleaning process and that pertaining to the plating process involve a necessity of bringing a chemical, such as a cleaning fluid or a plating fluid, into contact with interior surfaces of the blind holes. However, the semiconductor wafer that has not yet been immersed in a chemical remains dry, and interior surfaces of the respective blind holes also remain dry. When such a dry semiconductor wafer is immersed in a chemical, air traps including air bubbles are often formed inside the blind holes. Such an air trap corresponds to air bubbles building up at one location on the interior surface of the blind hole, thereby hindering the chemical from coming into contact with the entire internal surface of the blind hole. When the air traps have developed, failure to clean or plate the insides of the blind holes arises, which in turn results in lower reliability of a finished semiconductor device or a decrease in yield.
FIG. 1 of JP-A-5-299406 shows a proposed substrate cleaning bath which cleans a substrate by causing a cleaning fluid supplied from a cleaning fluid supply port of the substrate cleaning bath to flow parallel to the substrate through use of a straightening vane. JP-A-5-21413 also describes a proposed cleaning apparatus and method for cleaning a semiconductor substrate by causing a chemical to flow in parallel through use of a slit wall surface. However, these publications fail to describe a chemical processor and a chemical processing method for use with blind holes.